The present invention relates to a porous, thermoformable, heat sealable, nonwoven fabric. The fabric is useful in applications which require the controlled delivery of a material from within a container composed of the fabric.
Conventional fabric materials, for example, Reemay.RTM. 2420, used in making containers for the controlled delivery of products such as powders from within the container, consist of fabrics made from spunbonded polyester fibers. These conventional fabrics have a number of disadvantages for use in this type of application. The porosity of conventional spunbonded material is difficult to control because of web non-uniformity that is inherent in spunbonded fabric. As a result, a spunbonded fabric having a desired porosity is difficult to manufacture. Therefore, a container such as a pouch made of spunbonded polyester fibers would tend to allow amounts of the contained materials to escape through the fabric prior to the desired time for delivery of the contained product. Thus, the product may escape during product assembly, packaging and handling, while on the other hand, some product may be delivered too early, too late or not at all. For example, the present invention is useful in laundry systems, it being important in such an application that a detergent, bleach, or softener be delivered from a fabric pouch at the desired time.
Conventional polyester spunbonded fabrics also are not heat sealed, heat sealing taking place only at relatively high temperatures and at a relatively slow rate. Therefore, in order to form a container composed of spunbonded polyester fibers, it may be necessary to utilize costly adhesives to seal the spunbonded fabric together.